Rotatable horn antenna with feed moveable out of horn to form omnidirectional antenna



June & 192%? J. a. GEHMAN 33 A ROTATABLE HORN ANTENNA- WITH FEED MOVEABLE OUT OF HORN TO FORM OMNIDIRECTIONAL ANTENNA Filed Sept. 18, 1964 War/v Way/144M fiwsvrae.

Dynamics Corporation, Pomona, of Delaware Filed Sept. 1%, 1964, Ser. No. 397,584 12 Claims. (6i. 343729) Calif., a corporation This invention relates to antennas, particularly to convertible or dual function antennas, and more particularly to an antenna structure which is capable of radiating or receiving microwave energy in either a rotatable directional antenna pattern or an omnidirectional antenna pattern.

It sometimes is required that communication systems be capable of radiating or receiving energy in both an omnidirectional pattern or a directional pattern. In communication systems such as an airborne system, space and weight limitations necessitate the provision of an antenna means which can accomplish both of these functions with a minimum amount of equipment. It also is required that the antenna structure be adapted for mounting on an aircraft in such a way as to interfere as little as possible with the aerodynamics of the aircraft.

Therefore, it is an object of this invention to provide a compact lightweight antenna means for providing a rotatable directional antenna radiation pattern or an omnidirectional antenna pattern.

Another object of the invention is to provide a dual function antenna for mounting on an aircraft fuselage with a minimum of aerodynamic disturbance to said aircraft.

Another object of the invention is to provide a small compact antenna arrangement that can be easily converted for radiating energy in either an omnidirectional radiation pattern or a directional radiation pattern.

Another object of the invention is to provide a relatively simple compact antenna providing an omnidirectional antenna pattern or a directional antenna pattern rotatable through 360 of azimuth.

Other objects of the invention will become readily apparent from the following description and drawings wherein:

FIG. 1 is a view partially in cross section as taken on lines 1-1 of FIG. 2 and with parts cut away to illustrate an embodiment of the invention; and

FIG. 2 is taken along lines 2-2 of FIG. 1 and with portions thereof being cut-away to more clearly illustrate the invention.

The antenna comprises three flat, circular, conducting plates 10, 11 and 12 structurally connected in spatial relationship, one above the other on a common axis. The center and bottom plates 11 and 12 have centrally located and axially aligned orifices 13 and 14, respectively, to receive an extendable-retractable coaxial line antenna 15 having a radiation responsive surface 16 which is an approximately one-quarter wavelength portion of exposed coaxial cable center conductor, said surface 16 being capable of transmitting or receiving radiation energy. Integral with or attached to the center and bottom plates 11 and 12 is a horn type directional radiation reflector 17 (see FIG. 2) having side Walls 18 extending out to the edge of the plate perimeters and having its center adjacent the center orifices 13 and 14 of plates 11 and 12 so as to surround the antenna 15 at that point, thus furnishing directivity to radiated energy. Reflector 17 may, for example, be of the parabolic type, if desired. In order to choke or suppress unwanted side and back lobe radiation, the peripheral edges of the center and 3,324,474 Patented June 6, 1967 bottom plates 11 and 12 are slotted at wave depth around the plates.

Concentrically mounted on the undersurface of the bottom plate 12 is a gear 20 adapted to engage a drive gear 21 of a prime mover such as an electric motor 22 which is mounted on support structure 23 underneath plate 12, gear 20 being supported by structure 23 via bearings 24. The entire plate assembly revolves on a spin bearing indicated generally at 25 which is coaxially mounted on the undersurface of the bottom plate 12. The spin bearing 25 is supported by a housing 26 mounted below the plate assembly. The coaxial line antenna 15 is a telescoping rigid or line stretcher type cable and telescopes into a stationary coaxial line 27 mounted within housing 26 by movement of a handle 28 which is guided by slots 29 in housing 26, handle 28 being attached to the movable coaxial line 15. Handle 28 may be moved manually, or by mechanical or electrical means (not shown). Stationary coaxial line 27 is operatively connected through a coaxial-to-waveguide-transition element (not shown).

When the handle 28 is moved upwardly, the antenna 15 extends through the orifice 13 in the center plate 11 as shown in phantom in FIG. 1 and becomes omnidirectional. The uppermost plate 10 prevents the radiation pattern from having too much elevation. However, plate 10 may be removed, if desired. When the handle 28 is moved downwardly, the antenna 15 retracts to the lower plate position shown in solid lines in FIG. I and, in combination with the reflector 17, transmits a directional signal to selected receivers While the entire plate assembly spins on hearing 25.

To provide for protection and additional support, a layer of low dielectric material which does not inhibit radiation energy, such as polyfoam, indicated at 30, is positioned between plates 11 and 12 and is attached to these plates by a layer of epoxy, polyfoam 30 also being positioned within the walls of the reflector 17 as shown in FIG. 1. A plurality of low dielectric means such as plastic screws 31 which do not inhibit radiation energy interconnect the center and bottom plates 11 and 12, screws 31 being positioned behind reflector 17 as shown in FIG. 2. Top plate 10 is structurally attached to center plate 11 by a layer of polyfoam 32 via layers of epoxy. Means such as plastic screws 31 may also be utilized, if desired, to interconnect plates 10 and 11.

The plates 10, 11 and 12 may be made of solid material such as brass or copper, or printed circuit board techniques may be used wherein, for example, fiberglass boards are covered with thin shim stock of brass or copper. In order to provide for the quarter-wave choke slots by the circuit board technique, a lamination or sandwich of three sections could be fabricated wherein the top and bottom sections of one plate would have the full diameter required, while the middle section would be smaller by a quarter-wave length.

Various automatic means can be used to extend and retract the antenna. One arrangement might use two solenoids and an armature, with the combination acting in the usual manner to cause the antenna to telescope up and down as commanded by pulse inputs. Another arrangement might have a mechanical spiral attached to the movable coaxial line portion only, and also coupled to the drive motor through a proper gear selection. For example, as the motor turns clockwise the antenna rises until, at the end of the spiral, a ratchet arrangement is reached and all upward motion is stopped. Because the antenna is in the omnidirectional position at this point, there is no need for the plate assembly to rotate and the motor is stopped. When the motor is reversed, the reversing spiral moves the antenna downward to the directional position 19 to a quarterwhere another ratchet arrangement is reached and the plate assembly may continue to rotate.

It has thus been shown that this invention provides a simple, effective dual function antenna which is capable of radiating or receiving microwave energy in either a rotatable directional antenna pattern or an omnidirectional antenna pattern. This invention also eliminates the need of a conventional rotary joint arrangement between antenna and reflecting surface.

While the plates have ben shown and described as being circular, they may have any desired configuration, and the radiation reflector unit may take any desired form and may extend only a predetermined distance toward the periphery of the plates. Also, other types of radiation suppression means may be utilized. For example, a series of notches or slots or absorbent material may be used around all or portions of the periphery of the plates.

While the invention has been described with respect to rotating the plates 360, it is within the scope of this invention to utilize a system for oscillating the plates and associated radiation reflector arrangement, if desired. Also, additional plates may be utilized in combination with various types of reflective surfaces for changing the directivity of the radiation pattern as the antenna is extended or retracted selectively from one area to another. Furthermore, if desirable, the outer plate (plate may be provided with means to suppress unwanted side and back lobe radiation.

Although a particular embodiment of the invention has been illustrated and described, modifications will be apparent to those skilled in the art, and it is intended to cover in the appended claims all such modifications as come within the spirit and scope of the invention.

What I claim is:

1. A dual function antenna for radiating electro-magnetic energy in either a directional or an omnidirectional radiation pattern comprising first and second apertured, conductive plates secured in a spaced relationship with respect to each other; radiation reflector means disposed between said plates and extending radially toward the periphery of a portion of said plates; an extendable-retractable antenna means having a radiation responsive surface portion and adapted to move within the central apertures of said plates; means for at least partially rotating said plates; and means for selectively extending said antenna means from the area between said plates to an area external thereof or for retracting said antenna means from the area external of said plates.

2. The dual function antenna defined in claim 1 additionally including a third conductive plate coaxially aligned and secured in spaced relationship with one of said aforementioned plates, said third plate functioning to suppress elevation of the omnidirectional radiation pattern.

3. The dual function antenna defined in claim 1, wherein said first and second plates are provided with means to suppress leakage of wave energy at the periphery of said plates.

4. The dual function antenna defined in claim 3, where in said last mentioned means comprises a slot in the periphery of each of said plates.

5. The dual function antenna defined in claim 4, wherein the slot in each of said plates has a depth of a one-quarter wave length.

6. The dual function antenna defined in claim 1, wherein said radiation reflector means is of a horn-type configuration.

7. The dual function antenna defined in claim 1, wherein said antenna means is of a rigid telescoping coaxial cable type.

8. The dual function antenna defined in claim 1, wherein said means for at least partially rotating said plates includes gear means operatively connected to one of said plates, and prime mover means adapted to drive said gear means.

9. The dual function antenna defined in claim 1, wherein said antenna means extends into a housing, one of said plates being rotatably supported on said housing, and said means for selectively extending or retracting said antenna means being operatively positioned in said housing.

10. The dual function antenna defined in claim 1,

wherein said first and second plates are secured one to the other by a layer of low dielectric material operatively connected thereto.

11. The dual function antenna defined in claim 1, wherein said first and second plates are secured one to the other by a plurality of low dielectric attaching members.

12. A dual function antenna for radiating electro-magnetic energy in either a directional or an omindirectional radiation pattern comprising a pair of centrally apertured circular conductive plates secured in spaced relationship,

UNITED STATES PATENTS 3,141,169 7/1964 Bellis et al. 343766X ELI LIEBERMAN, Primary Examiner. 

1. A DUAL FUNCTION ANTENNA FOR RADIATING ELECTRO-MAGNETIC ENERGY IN EITHER A DIRECTIONAL OR AN OMNIDIRECTIONAL RADIATION PATTERN COMPRISING FIRST AND SECOND APERTURED, CONDUCTIVE PLATES SECURED IN A SPACED RELATIONSHIP WITH RESPECT TO EACH OTHER; RADIATION REFLECTOR MEANS DISPOSED BETWEEN SAID PLATES AND EXTENDING RADIALLY TOWARD THE PERIPHERY OF A PORTION OF SAID PLATES; AN EXTENDABLE-RETRACTABLE ANTENNA MEANS HAVING A RADIATION RESPONSIVE 